Polyimide oligomers are synthetic organic resins characterized by repeating imide linkages. Typically, such oligomers are end-capped with polymerizable chemical groups such as vinyl groups, amines, acetylenic groups, anhydride groups and the like. Polyimides prepared by crosslinking the oligomers are known for their outstanding chemical and physical properties, particularly their high temperature oxidative stability and strength. Polyimides are widely used as adhesives, molded articles, pre-cured films and fibers, curable enamels, laminating resins and as matrices for fiber-reinforced composites.
Prior art polyimide oligomers are disadvantageous in several respects. Typical prior art polyimide oligomers:                1. Are difficult to process. In contradistinction, the polyimide oligomers of the invention are readily processable as a melt and are thus suitable for resin transfer molding, resin infusion and other liquid processes. Moreover, the polyimide oligomers of the invention may be dissolved in common organic solvents such as methyl ethyl ketone, dimethyl formamide, glycol ethers, n-methylpyrrolidone and the like, thereby facilitating the processing of temperature-sensitive materials.        2. Require additional components in order to prepare cured polyimide articles. In contradistinction, the polyimide oligomers of the invention may be readily converted into the desired polyimide articles without any further components.        3. Require the addition of crosslinking agents to cure the oligomers. In contradistinction, the polyimide oligomers of the invention are readily curable by heat alone.        4. Have relatively high ionic conductivity. In contradistinction, the polyimide oligomers have relatively low ionic conductivities, generally in the range of about 50 to about 500 microSiemens per cm after aqueous ion extraction via methods typically used by those skilled in the art. Such low ionic conductivity makes the polyimide oligomers of the invention particularly suitable for a wide variety of encapsulation and molding applications, especially for the fabrication of parts for hybrid and electric vehicle applications.        
In addition, the polyimide oligomers of the invention are suitable for IC substrates and lead-free and halogen-free high layer count substrates, as well as for tooling applications and aerospace applications, friction materials and abrasive binders.